Charlotte Hale (Tessa Thompson) started Westworld as Delos' ruthless executive director. She ended it that way too, with the addition of "murderer" to her title. After she killed Elsie, Charlotte died in Westworld Season 2. But she'll continue to live on as a host in Season 3...we just don't know who's actually inside her body.
Following the hosts' uprising (and subsequent human massacre) at the end of Season 1, Charlotte was still alive when Season 2 picked up. As others rushed to mitigate the chaos, her number one prerogative was to track down Dolores' father Peter Abernathy, in whose head she'd stored some crucial data. Since Season 1, Charlotte had been helping Delos to copy the DNA of the park's human visitors. When behavior tech Elsie (who Bernard found still alive despite his Ford-ordered attack on her) learned of this secret plan, Charlotte shot her for not having the "moral flexibility" that was required to be a part of her Delos team.
Unfortunately, this was also Charlotte's undoing. After Bernard witnessed the murder, he built a host version of Charlotte and implanted Dolores' consciousness inside her body. It's this hybrid Charlotte-Dolores figure (aka Halores) who gunned down the real Charlotte in the end, just after she'd managed to reprogram Clementine to make the hosts turn on each other, succeeding in killing many of them.
This meant that throughout Season 2, we were unwittingly watching Halores, not Charlotte, in the timeline unfolding two weeks after the host uprising at the gala (so anytime after Bernard woke up on the beach). Once the real Charlotte was out of the picture, Dolores uploaded the remaining hosts to a secret location and left the park with five host consciousnesses (or "pearls") inside her purse. She also restored her original body, leaving it unclear who's now controlling Halores.
Apparently, not even Thompson knows who she's playing at this point. "I could be anyone, which is really fun," she told The Hollywood Reporter. "I have no idea who is inside of Charlotte after her shell leaves the park." Whoever it is, they appear to be closely aligned with Dolores in previews for Season 3, which can only mean double the danger.